"R. Mark Clayton" <nospamclayton@btinternet.com> wrote in messagenews:ccomg4$2mb$1@hercules.btinternet.com...>> "Harlan Osier" <maya_egg@hotmail.com> wrote in message> news:89ec59b9.0407092222.34e3fa@posting.google.com...> > Yes, 4 colors at 320*200 pixels.> >> > I cannot recommend it.>> Er should be 768x576, and probably 16bit colour, are you perhaps using an> old PC as a display?

In PAL-land DTV is nearer 720x576/704x576 non-square pixels (though some are540x576 to save bandwith) and the colour bit depth is effectively 24 bit -with 8 bit sampling of both luma and chroma difference signals (albeit withslightly less bit depth than 8 bits to allow for overshoot and undershoot -black is 16 not 0 and white is 235 not 255 - or is it 240 I can neverremember (I think 16-140 is the Colour difference range?) ).

Additionally because the luma resolution is twice that of the chroma bothvertically and horizontally - as 4:2:0 sampling is used for OTA DTV - only12 bits per luma sample are used to carry picture information i.e.. 4x8 bitluma "pixels" are accompanied by 1x8 bit Cr and 1x8bit Cb chroma sampleeach - so 4x8 + 2x8 = 48 bits per 4 pixels = 12 bits per pixel?

However the OPs observation is probably based on heavily compressed low datarate feeds that can and do look like they are made up of lego bricks ratherthan pixels. On the other hand some DTV can look cracking - though PCs areusually less than ideal viewing sources as they seldom cope with interlacedsource material that well.

"Stephen Neal" <stephen.neal@nospam.as-directed.com> wrote in messagenews:ccp2rl$1i3$1$830fa795@news.demon.co.uk...>> "R. Mark Clayton" <nospamclayton@btinternet.com> wrote in message> news:ccomg4$2mb$1@hercules.btinternet.com...> >> > "Harlan Osier" <maya_egg@hotmail.com> wrote in message> > news:89ec59b9.0407092222.34e3fa@posting.google.com...> > > Yes, 4 colors at 320*200 pixels.> > >> > > I cannot recommend it.> >> > Er should be 768x576, and probably 16bit colour, are you perhaps usingan> > old PC as a display?>> In PAL-land DTV is nearer 720x576/704x576 non-square pixels (though someare> 540x576 to save bandwith) and the colour bit depth is effectively 24 bit -> with 8 bit sampling of both luma and chroma difference signals (albeitwith> slightly less bit depth than 8 bits to allow for overshoot andundershoot -> black is 16 not 0 and white is 235 not 255 - or is it 240 I can never> remember (I think 16-140 is the Colour difference range?) ).>> Additionally because the luma resolution is twice that of the chroma both> vertically and horizontally - as 4:2:0 sampling is used for OTA DTV - only> 12 bits per luma sample are used to carry picture information i.e.. 4x8bit> luma "pixels" are accompanied by 1x8 bit Cr and 1x8bit Cb chroma sample> each - so 4x8 + 2x8 = 48 bits per 4 pixels = 12 bits per pixel?>> However the OPs observation is probably based on heavily compressed lowdata> rate feeds that can and do look like they are made up of lego bricksrather> than pixels. On the other hand some DTV can look cracking - though PCsare> usually less than ideal viewing sources as they seldom cope withinterlaced> source material that well.>> Steve>Yup, the SD digital channels can look very bad on an HD set and the coloralso needs some gamma correction. Many HD enthusiasts are screaming at thecable companies for requiring us to subscribe to channels we can't stand towatch just to get HD. The compression artifacts are almost unnoticeable onan analog set.

"Barry" <noozguru@earthlink.net> wrote in messagenews:VYWHc.11135$R36.6213@newsread2.news.pas.earthlink.net...>> "Stephen Neal" <stephen.neal@nospam.as-directed.com> wrote in message> news:ccp2rl$1i3$1$830fa795@news.demon.co.uk...> >> > "R. Mark Clayton" <nospamclayton@btinternet.com> wrote in message> > news:ccomg4$2mb$1@hercules.btinternet.com...> > >> > > "Harlan Osier" <maya_egg@hotmail.com> wrote in message> > > news:89ec59b9.0407092222.34e3fa@posting.google.com...> > > > Yes, 4 colors at 320*200 pixels.> > > >> > > > I cannot recommend it.> > >> > > Er should be 768x576, and probably 16bit colour, are you perhaps using> an> > > old PC as a display?> >> > In PAL-land DTV is nearer 720x576/704x576 non-square pixels (though some> are> > 540x576 to save bandwith) and the colour bit depth is effectively 24bit -> > with 8 bit sampling of both luma and chroma difference signals (albeit> with> > slightly less bit depth than 8 bits to allow for overshoot and> undershoot -> > black is 16 not 0 and white is 235 not 255 - or is it 240 I can never> > remember (I think 16-140 is the Colour difference range?) ).> >> > Additionally because the luma resolution is twice that of the chromaboth> > vertically and horizontally - as 4:2:0 sampling is used for OTA DTV -only> > 12 bits per luma sample are used to carry picture information i.e.. 4x8> bit> > luma "pixels" are accompanied by 1x8 bit Cr and 1x8bit Cb chroma sample> > each - so 4x8 + 2x8 = 48 bits per 4 pixels = 12 bits per pixel?> >> > However the OPs observation is probably based on heavily compressed low> data> > rate feeds that can and do look like they are made up of lego bricks> rather> > than pixels. On the other hand some DTV can look cracking - though PCs> are> > usually less than ideal viewing sources as they seldom cope with> interlaced> > source material that well.> >> > Steve> >> Yup, the SD digital channels can look very bad on an HD set and the color> also needs some gamma correction. Many HD enthusiasts are screaming atthe> cable companies for requiring us to subscribe to channels we can't standto> watch just to get HD. The compression artifacts are almost unnoticeableon> an analog set.

Interesting - the same complaint is levelled at some DTV transmissions inthe UK viewed on 100Hz sets. (In Europe we don't have many progressive, andalmost no HDTV, sets, but we do have 100Hz sets which upconvert 50Hzinterlaced to 100Hz interlaced to reduce large area flicker)

The digital processing used to convert a 50Hz interlaced picture to 100Hzalso emphasises (and in some cases adds to) existing compression artefactsintroduced by MPEG2 coding at low-to-medium data rates.

I wonder if US HDTVs are using similar digital processing when displaying480i material at 1080i or 720p? (I'm assuming US HDTV sets don't display480/60i SDTV in native mode and instead upconvert - I would be surprised ifthe TVs ran at both SDTV and HDTV scanning rates?)

> > I wonder if US HDTVs are using similar digital processing when displaying> 480i material at 1080i or 720p?

Some sets do marvelous upconversions. Mine does, realisticallyspeaking it is excellent. Currently Fox isdoing a 480i -> 720p at the station and it is very verymarvelous ... far better than DVD. In the fall they are goingto go to real 720p.

"Doug McDonald" <mcdonald@scs.uiuc.edu> wrote in messagenews:ccq0fp$h5l$1@news.ks.uiuc.edu...> Stephen Neal wrote:>> >> > I wonder if US HDTVs are using similar digital processing whendisplaying> > 480i material at 1080i or 720p?>> Some sets do marvelous upconversions. Mine does, realistically> speaking it is excellent.

Glad to hear it. Intellectually it struck me as easier to do a 480/50i to1080/50i scale without mangling the picture - whereas 576/50i to 576/100iinvolves interpolation of intermediate fields and lots of guestimating inthe temporal domain (which can go quite badly wrong)

I guess what your set is doing is similar to the DRC50/1250 settings onhigh-end DRC sets sold by Sony in the UK - which must be close to a 576/50ito 1152/50i scale - and this has always (to my eyes) looked better than thesame set in DRC100 mode (which is 576/50i to 576/100i) with far fewerprocessing artefacts.

> Currently Fox is> doing a 480i -> 720p at the station and it is very very> marvelous ...

Yep - if you have the bandwith much better to let the broadcaster do theupconversion :

1. They have an uncompressed (or lightly compressed) 480/60i source feed sowill only be scaling/frame rate converting the video and not the artefactsintroduced with broadcast compression (as would be the case if youupconverted an off-air signal)2. They will be using a broadcast quality upconverter rather than a coupleof dollars worth of in-TV DSP. Should be better quality.

> far better than DVD.

Yep - if it is sourced from a broadcast quality 480i feed, and the 720psignal is broadcast at a decent data rate, then it should outperform DVD,but is probably using 1.5-4 times the data rate of an average DVD master?

> In the fall they are going> to go to real 720p.

Good news.

Looks like we'll be waiting another year or two for HD services for the UK -though this may mean we get an MPEG4 or similar based system instead ofMPEG2 - though AIUI no decision has yet been made. (Sky have announced theirmove to HD - I suspect for movies and their main entertainment channel whichis mainly US imports, many of which are produced in HD? The BBC havesuggested they are considering it, and have announced a wish for allnon-soap drama to be produced in HD by 2006, and I guess most flagshipproductions will be HD, though the Beeb current policy is that extra costsfor HD production should be met by coproduction not the UK viewer/licencefee payer who can't watch in HD yet)

> > > Glad to hear it. Intellectually it struck me as easier to do a 480/50i to> 1080/50i scale without mangling the picture

Mine does NOT do 480i -> 1080i, it does 480@60i -> 720@60p

> > I guess what your set is doing is similar to the DRC50/1250 settings on> high-end DRC sets sold by Sony in the UK >

No, since my set is "progressive".

> >>Currently Fox is>>doing a 480i -> 720p at the station and it is very very>>marvelous ...> > > Yep - if you have the bandwith much better to let the broadcaster do the> upconversion :> > 1. They have an uncompressed (or lightly compressed) 480/60i source feed so> will only be scaling/frame rate converting the video and not the artefacts> introduced with broadcast compression

> 2. They will be using a broadcast quality upconverter rather than a couple> of dollars worth of in-TV DSP. Should be better quality.

I don't think this makes a difference ... the commercial ubiquitousFaroujda chips are excellent. The difference is in the uncompressedvideo coming in, with full resolution in all colors.

"Stephen Neal" <stephen.neal@nospam.as-directed.com> wrote in messagenews:ccr5md$dsq$1$830fa17d@news.demon.co.uk...>> "Doug McDonald" <mcdonald@scs.uiuc.edu> wrote in message> news:ccq0fp$h5l$1@news.ks.uiuc.edu...> > Stephen Neal wrote:> >> > >> > > I wonder if US HDTVs are using similar digital processing when> displaying> > > 480i material at 1080i or 720p?> >> > Some sets do marvelous upconversions. Mine does, realistically> > speaking it is excellent.>> Glad to hear it. Intellectually it struck me as easier to do a 480/50i to> 1080/50i scale without mangling the picture - whereas 576/50i to 576/100i> involves interpolation of intermediate fields and lots of guestimating in> the temporal domain (which can go quite badly wrong)>> I guess what your set is doing is similar to the DRC50/1250 settings on> high-end DRC sets sold by Sony in the UK - which must be close to a576/50i> to 1152/50i scale - and this has always (to my eyes) looked better thanthe> same set in DRC100 mode (which is 576/50i to 576/100i) with far fewer> processing artefacts.>> > Currently Fox is> > doing a 480i -> 720p at the station and it is very very> > marvelous ...>> Yep - if you have the bandwith much better to let the broadcaster do the> upconversion :>> 1. They have an uncompressed (or lightly compressed) 480/60i source feedso> will only be scaling/frame rate converting the video and not the artefacts> introduced with broadcast compression (as would be the case if you> upconverted an off-air signal)> 2. They will be using a broadcast quality upconverter rather than a couple> of dollars worth of in-TV DSP. Should be better quality.>> > far better than DVD.>> Yep - if it is sourced from a broadcast quality 480i feed, and the 720p> signal is broadcast at a decent data rate, then it should outperform DVD,> but is probably using 1.5-4 times the data rate of an average DVD master?>> > In the fall they are going> > to go to real 720p.>> Good news.>> Looks like we'll be waiting another year or two for HD services for theUK -> though this may mean we get an MPEG4 or similar based system instead of> MPEG2 - though AIUI no decision has yet been made. (Sky have announcedtheir> move to HD - I suspect for movies and their main entertainment channelwhich> is mainly US imports, many of which are produced in HD? The BBC have> suggested they are considering it, and have announced a wish for all> non-soap drama to be produced in HD by 2006, and I guess most flagship> productions will be HD, though the Beeb current policy is that extra costs> for HD production should be met by coproduction not the UK viewer/licence> fee payer who can't watch in HD yet)>> Steve>In hindsight they should have made one standard for all the world not basedon AC line frequency since that isn't needed anymore. Your computer doesn'tneed it so why should your TV?

Some of the new cable boxes are going to use MPEG-4 instead of MPEG-2 forHD.

Doug McDonald wrote:> Stephen Neal wrote:>>>>>>> Glad to hear it. Intellectually it struck me as easier to do a>> 480/50i to 1080/50i scale without mangling the picture>> Mine does NOT do 480i -> 1080i, it does 480@60i -> 720@60p

Aha - sorry - mis-applied assumption.

>>>>>> I guess what your set is doing is similar to the DRC50/1250 settings>> on high-end DRC sets sold by Sony in the UK>>>> No, since my set is "progressive".

Yep - as mentioned above.

>>>>>> Currently Fox is>>> doing a 480i -> 720p at the station and it is very very>>> marvelous ...>>>>>> Yep - if you have the bandwith much better to let the broadcaster do>> the upconversion :>>>> 1. They have an uncompressed (or lightly compressed) 480/60i source>> feed so will only be scaling/frame rate converting the video and not>> the artefacts introduced with broadcast compression>>>> 2. They will be using a broadcast quality upconverter rather than a>> couple of dollars worth of in-TV DSP. Should be better quality.>> I don't think this makes a difference ... the commercial ubiquitous> Faroujda chips are excellent. The difference is in the uncompressed> video coming in, with full resolution in all colors.

Err - but there is little difference between SDTV and HDTV in that respect.Either you get a component digital 480i SDTV signal or a component digital720p/1080i HDTV signal over a DTV channel surely - no NTSC or PAL compositeartefacts via either delivery method - no-one actually runs stationsanalogue these days do they ?

Certainly all UK digital TV platforms are digital component (and almost allTV production these days is digital component - barring some local stuff)and most set top boxes will output RGB analogue via their SCART connectors -offering a major quality improvement over analogue PAL reception (assumingdecent DTV data rates are used - which isn't always the case)

My observations are that the conversion from 576/50i RGB to 576/100i RGB(though whether this is via 576/50i and/or 100i YCrCb I'm not sure) thereare still observable artefacts introduced in every UK 100Hz set I have seen.I have also seen Faroudja scaling - thoug they aren't ubiquitous indirect-view CRT sold in Europe (I don't think Sony, Philips, Panasonic orJVC mention them in their UK bumph - though I may be wrong.) They are morelikely to be seen in the non-direct view arena (front/rear projection etc.)Do Faroudja do interlace->interlace conversion (i.e. 50->100 or 60->120?)

>>>>I don't think this makes a difference ... the commercial ubiquitous>>Faroujda chips are excellent. The difference is in the uncompressed>>video coming in, with full resolution in all colors.> > > > Err - but there is little difference between SDTV and HDTV in that respect.> Either you get a component digital 480i SDTV signal or a component digital> 720p/1080i HDTV signal over a DTV channel surely

I have no idea what those words mean. What do you mean by "you"? ...the ultimate home viewer of the station? The home viewergets MPEG2 digital, which has half the luma resolution bothvertical and horizontal, unless it is 480i, when the verticalcolor resolution is a quarter the possible (100% Kell factor)luma resolution.

- no NTSC or PAL composite> artefacts via either delivery method - no-one actually runs stations> analogue these days do they ?> Of course many stations are run analog these days. Most NTSCs are. Nobody in their right mind would convert a station to all-digital unless it were HDTV capable these days, at least network pass-thru HD. Yes, in the past some did. Many stations are convertingjust enough to digital to do network HD passthrough.

> Certainly all UK digital TV platforms are digital component (and almost all> TV production these days is digital component - barring some local stuff)> and most set top boxes will output RGB analogue via their SCART connectors -> offering a major quality improvement over analogue PAL reception (assuming> decent DTV data rates are used - which isn't always the case)>

Europe is not the US ... we have well over a thousand TV stations,of which probably a half are full-production capable,as opposed to you people who are almost all repeaters ...how many full TV stations with their own local productionfacilities are there in the UK?

> Do Faroudja do interlace->interlace conversion (i.e. 50->100 or 60->120?)

I have no idea. It certainly is not what they are usually usedfor, which is 480@60i -> 480@60p conversion with 2:3 pulldowndetection and fixup and full NTSC decoding (i.e. usingboth alternate lines and alternate frames, so-called "3D" ...which is not possible with PAL.)

Doug McDonald wrote:> Stephen Neal wrote:>>>>>>> I don't think this makes a difference ... the commercial ubiquitous>>> Faroujda chips are excellent. The difference is in the uncompressed>>> video coming in, with full resolution in all colors.>>>>>>>> Err - but there is little difference between SDTV and HDTV in that>> respect. Either you get a component digital 480i SDTV signal or a>> component digital 720p/1080i HDTV signal over a DTV channel surely>> I have no idea what those words mean. What do you mean by "you"? ...

Sorry - posting in the evening when tired and being a bit ambiguous.

What I was trying to convey was that surely the difference in received HDTV(1080/60i, 720/60p) and SDTV (480/60i, 576/50i) resolution and colour spacewas only the spatial scaling - with 4:2:0 MPEG2 being used for both - andthus both having full-gamut component digital outputs at the domesticreceiver. This only being the case if the SDTV feed were derived from adigital feed that hasn't been through an NTSC or PAL analogue path.

I accept what I think is your argument - that 4:2:2 480i scaled/upconvertedto 4:2:2 equivalent 720p then coded to 4:2:0 equivalent 720p for TX willlook better than 4:2:0 received MPEG2 480i scaled and upconverted to 720p4:2:2 equivalent at home.

> the ultimate home viewer of the station? The home viewer> gets MPEG2 digital, which has half the luma resolution both> vertical and horizontal, unless it is 480i, when the vertical> color resolution is a quarter the possible (100% Kell factor)> luma resolution.

Yep - though 4:2:2 MPEG2 is commonly deployed within the broadcast chains -either for contribution / distribution links - though 4:2:0 is oftendeployed as well for distribution - and also for server cacheing prior toTX. (Though the data rates are much higher than typical DVB / ATSC SD or HDtransmission rates - and short length GOPs are used, or I-frame only)...

Not sure what your luma resolution refers to - surely 4:2:2 SDTV broadcastas 4:2:0 SDTV via MPEG2 has the same resolution at the receiver as thebroadcast centre - there is no loss in horizontal luminance resolutionassuming 720x576 transmission is used (some broadcasters in the UK are using540x576 to save bandwith...)

>>> - no NTSC or PAL composite>> artefacts via either delivery method - no-one actually runs stations>> analogue these days do they ?>>> Of course many stations are run analog these days.

Ah - a major UK/US difference.

Most UK broadcasters are SDTV throughout - a process started in theearly-mid 90s as studios were upgraded. At that point a decision was takenby most broadcasters to move to digital production (and most studios beganbeing equipped with 4:3/16:9 switchable cameras). In the UK the only 4:3analogue production left in the mainstream broadcast arena are really theBBC local TV News outfits, though some of these are now 16:9 digital. Thelocal TV switching is engineered such that the DTV signal passes throughuntouched by PAL analogue footprints until the actual junction to localprogramming, on analogue the path is a little different - but the SDTV andanalogue versions of the BBC networks are distributed independently. (BBCanalogue is mainly sent to local broadcast centres as 140Mbslightly-compressed PAL digital - with occasionally 34Mbs used - whereas theSDTV signal is distributed at about 9Mbs MPEG2, and permanently decoded toSDI before recoding to 4.8Mbs CBR at each centre.)

> Most NTSCs are.

Ah - most PALs aren't... Certainly in the UK.

> Nobody in their right mind would convert a station to all-digital> unless it were HDTV capable these days, at least network pass-thru> HD. Yes, in the past some did. Many stations are converting> just enough to digital to do network HD passthrough.

Surely you can't get new analogue kit these days at a decent level though -so if you have to replace a local news gallery, or a small local productionstudio, you'd go SDTV rather than HD wouldn't you?

>>>>> Certainly all UK digital TV platforms are digital component (and>> almost all TV production these days is digital component - barring>> some local stuff) and most set top boxes will output RGB analogue>> via their SCART connectors - offering a major quality improvement>> over analogue PAL reception (assuming decent DTV data rates are used>> - which isn't always the case)>>>> Europe is not the US ... we have well over a thousand TV stations,> of which probably a half are full-production capable,> as opposed to you people who are almost all repeaters ...> how many full TV stations with their own local production> facilities are there in the UK?>

All BBC and ITV stations have local news production, usually a smallmulticamera studio with local editing, graphics, SNG/Microwave truck(s),etc. Some ITV (Granada, LWT, Anglia, Scottish, UTV, Meridian) stations havemedium-large multicamera studios for network / regional production - thoughsome of these are closing.

The BBC have major stations in London (two centres - currently about 16 or17 studios in the main one, Glasgow, Belfast and Glasgow)

I agree that the TV landscape is very different - but I am surprised at thelevel of analogue 4:3 NTSC kit still in use in the US - I'd have though thatMCR/Presentation in some areas had moved to digital to use modern automationsystems - and this would allow an SDTV network show to be delivered to anSDTV receiver with no analogue footprint, even if the local productionstudios were still analogue.

>> Do Faroudja do interlace->interlace conversion (i.e. 50->100 or>> 60->120?)>>> I have no idea. It certainly is not what they are usually used> for, which is 480@60i -> 480@60p conversion with 2:3 pulldown> detection and fixup and full NTSC decoding (i.e. using> both alternate lines and alternate frames, so-called "3D" ...> which is not possible with PAL.)

What is your view of the PAL Transform decoder developed by BBC R&D - it isa bit of a big beast but is a) reversible b) very high quality. BBC DVDs of70s and 80s tubed studio stuff recorded onto 2" Quad and 1" C format alllook cracking when decoded via this system.

> > Sorry - posting in the evening when tired and being a bit ambiguous.> > What I was trying to convey was that surely the difference in received HDTV> (1080/60i, 720/60p) and SDTV (480/60i, 576/50i) resolution and colour space> was only the spatial scaling - with 4:2:0 MPEG2 being used for both - and> thus both having full-gamut component digital outputs at the domestic> receiver.

Certainly digital OTA in the US is 4:2:0 MPEG2.

>This only being the case if the SDTV feed were derived from a> digital feed that hasn't been through an NTSC or PAL analogue path.

Well, it certainly has not been through the un-recoverableform of PAL. NTSC is a very different matter. Yes, some of it ...in fact a lot of it ... probably has been through NTSC composite,but NOT OTA NTSC composite: it probably was NTSC composite witha full 1.5 MHz bandwith chroma in both I and Q. Even cheap consumer grade chips do a fine job of recovering the full signal from this, thanks to the brilliant design of NTSC which does not havethe hopelessly complicated phase shifts of PAL. In our town,all the non-HD channels derive their digital signal from NTSC.This is of course clearly nowhere near as good as what Foxcurrently does, which is derive the digital from a top-gradedigital signal in which R, G, and B are all full resolution ...truly 480x720 in all three.

> > I accept what I think is your argument - that 4:2:2 480i scaled/upconverted> to 4:2:2 equivalent 720p then coded to 4:2:0 equivalent 720p for TX will> look better than 4:2:0 received MPEG2 480i scaled and upconverted to 720p> 4:2:2 equivalent at home.

I'm not sure what 4:2:2 means ... what I am told Fox does issend out digital in which all three channels are the full480x720 resolution.

>>>>>>>Of course many stations are run analog these days.> > > Ah - a major UK/US difference.

> In the UK the only 4:3> analogue production left in the mainstream broadcast arena are really the> BBC local TV News outfits, though some of these are now 16:9 digital.

Well, in the US the only 4:3 analog production left in the mainstream broadcast arena are really thelocal TV outfits, which are not all necessarily news ... we havea PBS station that does many, many hours a week of local non-newsproduction. I don't know if this PBS station is digital or not ... they recently moved to a new plant, so I suspect it is. Our secondclosest PBS station is definately converting to digital, andapparently will have a modest News/sports truck that is HD[for local production of college sports, hence the "modest".]

BUT ..... Local "News" is a huge, gigantic part of US TV production!

> Surely you can't get new analogue kit these days at a decent level though -> so if you have to replace a local news gallery, or a small local production> studio, you'd go SDTV rather than HD wouldn't you?>

Well, in most cases yes, but in some markets there may simplybe no money .... if an analog camera, for example, dies, they'sjust get a used unit or a pro-sumer type. All they money gotspent for the mandated DTV transmitter!

>>>Certainly all UK digital TV platforms are digital component (and>>>almost all TV production these days is digital component - barring>>>some local stuff)

But we in the US have scads and scads of "local", some of itpretty low-budget.

>>and most set top boxes will output RGB analogue>>>via their SCART connectors -No STB in the US currently outputs RGB analog .... onlycomponent analog. This is to keep, as far as possible,a split between computer and TV equipment, to preventexonomies of scale. There are TV monitors that dotake computer RGB analog, however. Note that in theUS computer and TV DVI are different (though most certainlynot incompatible ... just enough different to be a nuisance.)

> > I agree that the TV landscape is very different - but I am surprised at the> level of analogue 4:3 NTSC kit still in use in the US - I'd have though that> MCR/Presentation in some areas had moved to digital to use modern automation> systems - and this would allow an SDTV network show to be delivered to an> SDTV receiver with no analogue footprint, even if the local production> studios were still analogue.

There is little point in that, except, previously, for Fox stations.It's either go the cheapest possible route (convert analogto digital AT THE TRANSMITTER BUILDING, post-analog-STL),go full digital (though not HD production, just all digitalswitching that is HD capable), or the intermediate step ofjust enough digital to get a network HD feed to a switcherthat switches from an analog-digital convertor that isafter the entire pre-conversion local analog plant. Manystations are doing the last.

> > What is your view of the PAL Transform decoder developed by BBC R&D - it is> a bit of a big beast but is a) reversible b) very high quality. BBC DVDs of> 70s and 80s tubed studio stuff recorded onto 2" Quad and 1" C format all> look cracking when decoded via this system.

My opinion is that your PAL was a serious silliness ... deployed just as the "problem" it was supposed to cure became a non-issue,just as your DAB was a mistake ... a SERIOUS mistake ... andthe higher bitrate parts of DVB-T are a mistake. MPEG-2 isnot, of course, a mistake compared of modern better stuff,it is all there was and still there is no way to ensure"upgradeability". When the TV does deploy a mobile-capableSTDV service, it will be with a better codec.

"Doug McDonald" <mcdonald@scs.uiuc.edu> wrote in messagenews:ccu51m$of$1@news.ks.uiuc.edu...> Stephen Neal wrote:>> >> > Sorry - posting in the evening when tired and being a bit ambiguous.> >> > What I was trying to convey was that surely the difference in receivedHDTV> > (1080/60i, 720/60p) and SDTV (480/60i, 576/50i) resolution and colourspace> > was only the spatial scaling - with 4:2:0 MPEG2 being used for both -and> > thus both having full-gamut component digital outputs at the domestic> > receiver.>> Certainly digital OTA in the US is 4:2:0 MPEG2.

Yep - same as the UK.

>>> >This only being the case if the SDTV feed were derived from a> > digital feed that hasn't been through an NTSC or PAL analogue path.>> Well, it certainly has not been through the un-recoverable> form of PAL. NTSC is a very different matter. Yes, some of it ...> in fact a lot of it ... probably has been through NTSC composite,> but NOT OTA NTSC composite: it probably was NTSC composite with> a full 1.5 MHz bandwith chroma in both I and Q. Even cheap consumer> grade chips do a fine job of recovering the full signal from this,> thanks to the brilliant design of NTSC which does not have> the hopelessly complicated phase shifts of PAL.

Yep - but it still has the appalling chroma bandwith reduction, and inherentlimitations of sub-carrier based encoding (even S-video has most of these)irrespective of it being PAL or NTSC.

I had imagined that more US SDTV stuff was free of composite artefacts - ifnothing else the inherent subcarrier artefacts that even high-qualitydecoding suffers from means MPEG2 encoding is less efficient (as you areencoding artefacts rather than picture detail)

> In our town,> all the non-HD channels derive their digital signal from NTSC.

> This is of course clearly nowhere near as good as what Fox> currently does, which is derive the digital from a top-grade> digital signal in which R, G, and B are all full resolution ...> truly 480x720 in all three.

Surely 4:2:2 YCrCb is what Fox run isn't it? What VT format are they usingthat runs 4:4:4 RGB rather than 4:2:2 YCrCb? (I know there was someexperimental D1 stuff running 4:4:4 SDTV - but I didn't think it wasmainstream) Standard SDTV SDI (i.e. 270Mbs) digital video used to connectSDTV VTRs, Vision Mixers, cameras, still stores etc. runs on the basis of4:2:2 sampling rather than 4:4:4 - where two interconnects are required(which is normally limited to telecine ->colour corrector connection etc.)

>> >> > I accept what I think is your argument - that 4:2:2 480iscaled/upconverted> > to 4:2:2 equivalent 720p then coded to 4:2:0 equivalent 720p for TX will> > look better than 4:2:0 received MPEG2 480i scaled and upconverted to720p> > 4:2:2 equivalent at home.>> I'm not sure what 4:2:2 means ... what I am told Fox does is> send out digital in which all three channels are the full> 480x720 resolution.

4:2:2 is the standard broadcast digital sampling structure used for SDTVbroadcast video. The RGB camera output is matrixed to Luminance (Y) andColour Difference Cr (R-Y) and Cb (B-Y) signals. The Luminance signal issampled at 13.5MHz, the Chrominance signals are both sampled at 6.75MHz -i.e. there is twice as much luminance resolution horizontally thanchrominance. Therefore for every two luminance (Y) samples there is a singlepair of Cr (B-Y) and Cb (R-Y) samples - or in data terms one luma sample ispaired with a Cr sample, the next with a Cb (though the chroma samples aredeemed to be co-sited) The vertical chroma resolution is not reduced - andremains the same as the luminance resolution. This gives a luminanceresolution of 720x480 or 720x576, and a chroma resolution of 360x480 or360x576.

4:2:0 is used in some VT formats (miniDV) and for OTA MPEG2 SDTVtransmission. This works by halving the VERTICAL chroma resolution as well,so that the chroma resolution is reduced equal horizontal and verticallyrelative to the luminance resolution (reducing the bandwith requirementnoticably). Thus the luminance remains 720x480/576 but the chroma isreduced to 360x240/288.

If the 480/60i to 720/60p conversion is done with a 4:2:2 480/60i source (aswould be the case at a broadcast centre) there is more vertical chromaresolution to take advantage of (and fewer compression artefacts) than ifthe conversion is done in the home where the 480/60i source is 4:2:0 andthus has half the vertical chroma resolution.

Fox will still then be broadcasting the 720/60p in 4:2:0 (or the equivalentscaled HD version - for some reason 4:2:0 is still often used rather than16:8:0 or whatever the equivalent is) via MPEG2 and the resolutions wouldthus be 1280x720 luminance, 640x360 for the chrominance. I don't see howFox can broadcast a 4:4:4 RGB signal over ATSC (I don't think the forms ofMPEG2 used allow 4:4:4 in either RGB or YCrCb chroma spaces), nor do I seehow they'd source the material in 4:4:4 720x480/60i using conventionalstandard SDTV broadcast production kit.

> >>>> >>> >>Of course many stations are run analog these days.> >> >> > Ah - a major UK/US difference.>> > In the UK the only 4:3> > analogue production left in the mainstream broadcast arena are reallythe> > BBC local TV News outfits, though some of these are now 16:9 digital.>> Well, in the US the only 4:3 analog

I'm happy for you to convert my TV programmes to your "programs" and myanalogue production to your "analog" - can't help spelling the way I wasbrought up to though.

> production left in the mainstream broadcast arena are really the> local TV outfits, which are not all necessarily news ... we have> a PBS station that does many, many hours a week of local non-news> production. I don't know if this PBS station is digital or not ...> they recently moved to a new plant, so I suspect it is. Our second> closest PBS station is definately converting to digital, and> apparently will have a modest News/sports truck that is HD> [for local production of college sports, hence the "modest".]>> BUT ..... Local "News" is a huge, gigantic part of US TV production!

Yep - less so in the UK - where the Network and Local Newscasts on bothchannels are kind of more integrated and more national/international andless local. (Our longest regional news bulletin is about 30 mins in the UKon both BBC One and ITV1 - spread over about 17-25 regions. This directlyfollows a networked national newscast - there is no tradition of local newsteams covering national stories - as national stories - in theirprogrammes - they leave that to the network shows unless there is adifferent regional angle that it is relevant for them to cover.)

You are right - it is a major difference - the UK is a smaller country, andits whole TV landscape is sculpted around national networks rather thanaffiliates.

>>> > Surely you can't get new analogue kit these days at a decent levelthough -> > so if you have to replace a local news gallery, or a small localproduction> > studio, you'd go SDTV rather than HD wouldn't you?> >>> Well, in most cases yes, but in some markets there may simply> be no money .... if an analog camera, for example, dies, they's> just get a used unit or a pro-sumer type. All they money got> spent for the mandated DTV transmitter!

Yep - the price paid for lots of local TV stations is that they arepresumably less well-funded. That said many BBC English regions stillrunning 4:3 PAL analogue kit are using galleries built in thelate-80s/early-90s - two or three regions only ditched their last tubedcameras for CCDs in the last couple of years, and the BBC is still using ahell of a lot of analogue component Beta SP gear locally and nationally(even for 16:9 production)

>> >>>Certainly all UK digital TV platforms are digital component (and> >>>almost all TV production these days is digital component - barring> >>>some local stuff)>> But we in the US have scads and scads of "local", some of it> pretty low-budget.

Yep - a major difference. I think our budget range is smaller than the US -our local TV stations are probably less local, but better equipped, but ourhigh-end productions are probably lower budget to. The move to 16:9 SDTV(which is now a large majority of all the major UK networks output) ratherthan HDTV allowed a change-over earlier and more quickly - though I suspectHDTV is coming quicker than many were expecting. A couple of Frenchnetworks have announced they are moving to MPEG4 based HD next year - havingalready negotiated HD rights to their movies and imported shows already.

> >>and most set top boxes will output RGB analogue> >>>via their SCART connectors -> No STB in the US currently outputs RGB analog .... only> component analog. This is to keep, as far as possible,> a split between computer and TV equipment, to prevent> exonomies of scale.

Ah - we've had RGB analogue since the early 80s - as part of thePeritel/SCART standard. It initially came about to allow external monitors(like the Sony Profeel) to be fed Videotext/Teletext in quality, andanalogue RGB (via SCART or DIN) was popular with 80s home computers thatused TVs as monitors. I fondly remember the move from UHF modulator toComposite video and then RGB analogue with mine!

When DVD arrived almost universally players came with RGB output, as did settop boxes for D/D2MAC analogue component satellite transmissions, and thenDVB boxes.

Although it is a horrible connector - it does have great benefits for usersimplicity. A single connector can carry composite video, stereo audio (intwo directions at the same time), as well as widescreen switching and statusswitching. When used in RGB mode it becomes directional. It makesconnecting VCRs,DVD players and STBs to TVs pretty easy (my Mum can do it)and a lot easier than the 5xRCA phonos required for analogue component (or6xRCA phonos required for Composite+Stereo audio in and out for VCRs)

As a result the triple phono component analogue connection is less popular -though is the defacto standard for PAL progressive interconnects - the ruleseems to be SCART = interlaced SDTV res, Component = progressive or HD.

> There are TV monitors that do> take computer RGB analog, however. Note that in the> US computer and TV DVI are different (though most certainly> not incompatible ... just enough different to be a nuisance.)>

Yep - not much DVI video stuff around in the UK yet - just the odd HDTV settop box for the Euro 1080 broadcasts.

>> >> > I agree that the TV landscape is very different - but I am surprised atthe> > level of analogue 4:3 NTSC kit still in use in the US - I'd have thoughthat> > MCR/Presentation in some areas had moved to digital to use modernautomation> > systems - and this would allow an SDTV network show to be delivered toan> > SDTV receiver with no analogue footprint, even if the local production> > studios were still analogue.>> There is little point in that, except, previously, for Fox stations.> It's either go the cheapest possible route (convert analog> to digital AT THE TRANSMITTER BUILDING, post-analog-STL),> go full digital (though not HD production, just all digital> switching that is HD capable), or the intermediate step of> just enough digital to get a network HD feed to a switcher> that switches from an analog-digital convertor that is> after the entire pre-conversion local analog plant. Many> stations are doing the last.>

However - surely there must be local TV stations that can't afford to go HDfor production but need to upgrade ailing analogue production kit? Surely amove to SDTV would make sense for them? Certainly a lot of SDTV US sitcomand drama looks to be produced SDTV rather than analogue NTSC - no compositeartefacts to be seen on standards conversions that make it over here (andthey don't get PAL footprints on the way to my TV!) - but I guess productionhouses moved to digital a lot earlier than stations.

I think that SDTV production with HDTV digital presentation would make senseto a lot of people - the improvement in SDTV relative to analogue NTSC inproduction would still be marked - and SDTV upconverted to HD will look alot better than NTSC upconverted to HD.

The last suggestion is effectively what the BBC supplied all of theiranalogue regional stations with when they launched regional output on theDVB-T version of BBC One (until then a pan-UK "best of the local news" hadfilled regional slots on the digital version of the network). All theregions were given small SDTV switchers and Aspect Ratio Converters to allowthem to switch from the 16:9 SDTV network feed to a delayed-and-ARCed-to14:9SDTV output from the 4:3 PAL analogue studio for the duration of theregional show. (This is complicated by the need for a switch to also takeplace on the separate analogue network feed, so a fixed video delay andswitch delay was introduced to the regional digital studio chain tocompensate for coding latency in the digital chain)

> >> > What is your view of the PAL Transform decoder developed by BBC R&D - itis> > a bit of a big beast but is a) reversible b) very high quality. BBCDVDs of> > 70s and 80s tubed studio stuff recorded onto 2" Quad and 1" C format all> > look cracking when decoded via this system.>> My opinion is that your PAL was a serious silliness ... deployed> just as the "problem" it was supposed to cure became a non-issue,> just as your DAB was a mistake ... a SERIOUS mistake ... and> the higher bitrate parts of DVB-T are a mistake.

Can't agree there - PAL was a very effective compromise that has servedEurope incredibly well. The BBC recently showed some of their earlyWimbledon coverage - 67,68 etc. - and it stands up incredibly well totoday's stuff. The US NTSC stuff I have seen from the same era doesn't holdup as well - but it is difficult to say if this is a problem with NTSC perse or the cameras (which seemed to be based on Image Orthicons and/orVidicons rather than Plumbicons)

But we always differ on this point. I think we were lucky to chose a widerchannel spacing in Europe that allowed a wider luminance bandwith (and ahigher chroma subcarrier to be used) - but that is not a PAL issue (we couldhave run NTSC 4.43 as the BBC initially envisaged) but the more robustnature of PAL did pay big dividends. I think we benefited in the early daysbecause cameras designed for PAL had to be sharper (again not because theywere PAL but because PAL meant wider bandwith effectively), and were oftenbetter engineered than the cameras engineered for NTSC. Certainly in the70s Philips, Fernseh, Link and Marconi cameras seemed to do better than RCAsin the picture quality stakes in Europe. (I think the European manufacturersalso started later in the design stakes, so were selling devices based onmore modern technology)

NTSC may be easier to decode - but it is also easier to mangle in adistribution and transmission chain. The average NTSC OTA or NTSC cablepicture I have seen when visiting the US has, sadly, always been softer andof far poorer colour quality (not sure if this is IQ vs UV processing, orthe use of autotint type hue-tracking controls) than the PAL picture inequivalent situations. (And I don't mean hotel rooms - their TV pictures arenormally lousy the world over...)

NTSC analogue (and composite digital) as a production format is muchbetter - and you are right, when well looked after it delivers goodpictures. Problem is it is often not well looked after. 720x480i digitalproduction is excellent - and apart from the coarser line structure(especially noticable on letterboxed 16:9 material) - not an issue.

The pictures delivered by a PAL transform decoder do look cracking whenviewed from DVD - I don't have access to equivalent NTSC video from the sametime zone - with the exception of the PBS Cosmos DVDs - which also look verygood (though a good bit softer)

> MPEG-2 is> not, of course, a mistake compared of modern better stuff,> it is all there was and still there is no way to ensure> "upgradeability". When the TV does deploy a mobile-capable> STDV service, it will be with a better codec.

Looks like a DVB-T receiver for mobile use is about to appear on the Germanmarket - tests show it received all 21 channels on their DTT system (whichruns at a lower data rate in narrower channels than the UKs, but is similar)

>>Well, it certainly has not been through the un-recoverable>>form of PAL. NTSC is a very different matter. Yes, some of it ...>>in fact a lot of it ... probably has been through NTSC composite,>>but NOT OTA NTSC composite: it probably was NTSC composite with>>a full 1.5 MHz bandwith chroma in both I and Q.

> Yep - but it still has the appalling chroma bandwith reduction,

As I said, not necessarily. Non-broadcast NTSC may havea full 1.5 MHZ in both sidebands of I and Q.

> and inherent> limitations of sub-carrier based encoding (even S-video has most of these)> irrespective of it being PAL or NTSC.

S-video subcarrier encoding has no significant limitations,even with a 3.58 MHz subcarrier. 3 MHz color bandwidthin both I and Q is just fine for even a 7 MHz luma.

> > I had imagined that more US SDTV stuff was free of composite artefacts - if> nothing else the inherent subcarrier artefacts that even high-quality> decoding suffers from means MPEG2 encoding is less efficient (as you are> encoding artefacts rather than picture detail)>

High quality decoding of even composite NTSC is very, very goodindeed, if it is not OTA bandwidth limited. Indeed,for static pictures it it essentially a perfect decode.

> >>In our town,>>all the non-HD channels derive their digital signal from NTSC.> > > Ah - few of the DTV stations in mine have detectable composite artefacts (I> think Sky Sports News does) - certainly the main UK networks (BBC One, Two,> Three, Four, News 24, CBBC, CBeebies, ITV1, ITV2, Channel Four, Five)> don't - apart from on some news contributions that use legacy links gear.> > >>This is of course clearly nowhere near as good as what Fox>>currently does, which is derive the digital from a top-grade>>digital signal in which R, G, and B are all full resolution ...>>truly 480x720 in all three.> >

>>>>I'm not sure what 4:2:2 means ... what I am told Fox does is>>send out digital in which all three channels are the full>>480x720 resolution.> > > 4:2:2 is the standard broadcast digital sampling structure used for SDTV> broadcast video. The RGB camera output is matrixed to Luminance (Y) and> Colour Difference Cr (R-Y) and Cb (B-Y) signals. ..... [snip] This gives a luminance> resolution of 720x480 or 720x576, and a chroma resolution of 360x480 or> 360x576.> > > Fox will still then be broadcasting the 720/60p in 4:2:0

There is zero doubt about that: you are correct.

> I don't see how> Fox can broadcast a 4:4:4 RGB signal over ATSCThey don;t

>nor do I see> how they'd source the material in 4:4:4 720x480/60i using conventional> standard SDTV broadcast production kit.

They don't, I am told. The only high resolution stuffis telecines 35 mm 24 Hz film. Sometimes they doupconvert true TV camera video for sports, and the result ishorrible.

In article <ce9312$oqv$1@news.ks.uiuc.edu>, Doug McDonald <mcdonald@scs.uiuc.edu> writes:> Stephen Neal wrote:> >>>Well, it certainly has not been through the un-recoverable>>>form of PAL. NTSC is a very different matter. Yes, some of it ...>>>in fact a lot of it ... probably has been through NTSC composite,>>>but NOT OTA NTSC composite: it probably was NTSC composite with>>>a full 1.5 MHz bandwith chroma in both I and Q. > > >> Yep - but it still has the appalling chroma bandwith reduction,> > As I said, not necessarily. Non-broadcast NTSC may have> a full 1.5 MHZ in both sidebands of I and Q.>The effect of the I and Q bandwidth reduction isn't quite assevere as it might superficially appear to be. The axis(sp) arewell chosen. Considering the technology of the day, they dida wonderful job of packing video into a small place. :-).

>> >> I had imagined that more US SDTV stuff was free of composite artefacts - if>> nothing else the inherent subcarrier artefacts that even high-quality>> decoding suffers from means MPEG2 encoding is less efficient (as you are>> encoding artefacts rather than picture detail)>> > > High quality decoding of even composite NTSC is very, very good> indeed, if it is not OTA bandwidth limited. Indeed,> for static pictures it it essentially a perfect decode.>One other thing:

The technology needed to do a full NTSC decode is significantlydifferent from the typical PAL decoder. This means that PAL TVsets that also do an NTSC decode (with the fancy multi-line LINE-COMBS)cannot really do justice when compared with a full NTSC comb. Theline-comb is a BACKUP DECODING MODE for significant movement whencompared to the very good 3D combing. It is interesting when lookingat the effects of full 3D decode when compared with almost any linecomb. The diagonal resolution is nearly perfect with a 3D decode.

>No STB in the US currently outputs RGB analog .... only>component analog.

True, but only because of a technicality. The RCA DTC-100, which was the first (and, to this day, probably the least troublesome and buggy) OTA/DirecTV high definition set-top box had a VGA RGB output for high definition. It had no component output. The technicality that saves your statement: the DTC-100 is now discontinued.

Robert Orban wrote:> In article <ccu51m$of$1@news.ks.uiuc.edu>, mcdonald@scs.uiuc.edu says...> > >>No STB in the US currently outputs RGB analog .... only>>component analog.> > > True, but only because of a technicality. The RCA DTC-100, which was the first > (and, to this day, probably the least troublesome and buggy) OTA/DirecTV high > definition set-top box had a VGA RGB output for high definition. It had no > component output. The technicality that saves your statement: the DTC-100 is > now discontinued.>

The Samsung T-150 also had an RGB output ... and it toois long discontinued. That's why I said "currently".